The elegant demonstration by Milkovich et al that graft copolymers can be prepared by the copolymerization of macromonomers with conventional small monomers has initiated a spate of publications in this field. Particular interest has been focussed upon the radical polymerizations of vinyl monomers because it was expected that the rate of polymerization and the degree of polymerization on the molecular weight (Mn) of the growing polymer may be substantially the same as that of conventional vinyl monomers. Both the rate and the degree of polymerization are generally quite high for vinyl monomers which are therefore of major economic interest. The realization that a large moiety adjacent the vinyl head group often reduces the rate of polymerization of the macromer because of the relatively low molar concentration of reactive end groups, particularly at high conversions where also the increased viscosity of the reaction mass reduces the diffusion of the macromer to the reaction site, has done nothing to dull this interest.
In particular, functional polymers having either pendant or terminal triple bonds have received much attention recently, and especially the latter, because of their potential use in the development of matrix resins for lightweight composite materials. Thermal curing based on the properties of triple bonds is characteristically free of evolution of volatile byproducts, wherein lies their advantage. A review article titled "Acetylene Containing Precursor Polymers" by P. M. Hergenrother, J. Macromol. Sci-Rev. Macromol. Chem., C19(1), 1-34 (1980) discloases a variety of acetylenic polymers. Despite this interest and the known advantage (see P. M. Hergenrother, J. Polym. Sci., Polym. Chem. Ed., 13, 1095, 1980; and, id. 20 3131, 1982) the only publications dealing with pendant ethynyl groups are on aromatic polyetherketone-sulfones (see "Aromatic Polyethers, Polysulfones, and Polyketones as Laminating Resins. V. Polymers Containing Acetylenic Side Groups" by C. Samyn and C. S. Marvel, J. Polym. Sci., Polym. Chem. Ed, 13, 1095, 1975), and "Sulfone-Ester Polymers Containing Pendant Ethynyl Groups" by B. J. Jensen and P. M. Hergenrother, Polymer Preprints 25 No. 2, August 1984. The Samyn et al procedure relies on converting acetyl groups introduced in the backbone into acetylenic groups, is far less convenient than the process I have outlined herein, and the materials produced starting with 2,4-diphenoxyacetophenone in the backbone are unlike the ones produced by my process.
A three-step procedure for the synthesis of acetylene terminated polymers is disclosed in Report AFWAL-TR-83-4159 titled "Low Cost Acetylene Terminated Polymers" by J. F. Prescott et al, issued by Air Force Wright Aeronautical Laboratories, in which synthesis palladium and copper must be disposed of.
The particular interest of my invention is to tailor a polyarylene polyether ("PAPE") oligomer with pendant vinyl or ethynyl groups, or a PAPE oligomer which may have both pendant and terminal vinyl or ethynyl groups, all referred to herein as "functional" groups. Such an oligomer was deemed desirable not only because it should be thermally crosslinkable through its vinyl groups, or ethynyl groups, but because it might also melt at a temperature in the range from about 200.degree. C. to about 300.degree. C., yet be capable of withstanding thermal degradation at a temperature in the range from above 300.degree. C. to about 400.degree. C.
This invention is more particularly related to polyfunctional polymers of dihydroxybenzene, dihydroxynaphthalene, and diphenols, all referred to herein as dihydric phenols (DHP), and the corresponding sulfur (thio) compounds referred to as polydihydric thiophenols (DHTP); and, of 2,6-dimethylphenol (DMP) and like 2,6-disubstituted phenols referred to herein as mononuclear monohydric phenols (MHP). These polymers have a Mn (number average mol wt) less than about 50,000, hence termed oligomers. They are relatively low Mn known polymers (oligomers) which are analogous to the relatively high Mn PAPEs disclosed in U.S. Pat. No. 4,108,837 relevant portions of the disclosure of which are incorporated by reference thereto as if fully set forth herein. By "polyfunctional oligomers" I refer to those having at least two, and preferably up to about 12 pendant vinyl or ethynyl groups per oligomer; and, optionally, such oligomers may additionally also include at least one terminal vinyl or ethynyl group. For example, poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) will have only one terminal functional group, but may have plural pendant groups.
One or the other DHP and DHTP, or both, are referred to herein as "DH(T)P" for brevity. Such oligomers are defined herein as polymers containing from 2 to about 100 repeating units each having the formula --DH(G)P R.sup.s --, where R.sup.s represents the residue of a linking group. These oligomers contain at least three phenyl or thiophenyl rings which may have inert substituents, each ring linked to another through an O, Si, C or S atom. Such DHP and DHTP oligomers, also termed poly[DH(T)P], or [DH(T)P].sub.n, are terminated at each end (hence "di-terminated") with a phenol (Ph) or thiophenol (TPh) group respectively, or with a chlorophenyl or bromophenyl, hence halophenyl (HPh) group, any of which groups may have inert substituents. For brevity, "di-(T)Ph-terminated" refers herein to either or both oligomers which are Ph- and TPh-terminated respectively; and "di-HPh-terminated" refers to oligomers which are terminated at each end with a halophenyl group.
Various considerations relating to providing a di-(T)Ph-terminated poly[DH(T)P] with functional vinyl or ethynyl terminal (end) groups are set forth in my copending patent application Ser. No. 586,678 filed Mar. 7, 1984 the disclosure of which is incorporated by reference thereto as if fully set forth herein; and in references cited in the application, relevant portions of which references are similarly incorporated. As in that invention, the DH(T)P reactant(s) herein are poorly soluble in commonly available organic solvents, and anhydrous DMSO or other aggressive solvent, is used for preparation of the poly[DH(T)P] oligomer, particularly where two DH(T)P are polycondensed, for example, 4,4'-isopropylidenediphenol (also, 2,2-bis(4-hydroxyphenyl) propane, or bisphenol A, BPA) and 4,4'-dichlorodiphenyl sulfone DCPS derived from diphenyl sulfone DPS. The reaction is very fast, and the nucleophilic displacement step-growth polymerization quickly reaches relatively high mol wt in the range from about 1000 to about 20,000, and 100% yield. The polymer weight is relatively independent of the ratio between the nucleophilic and electrophilic reactants. Most importantly, the organic-soluble polymer obtained may be made with only electrophilic species as chain ends, independent of the reaction yield but dependent upon the reactant ratio. Such poly[DH(T)P] are particularly well suited for being modified to contain only pendant vinyl or ethynyl groups, or both pendant and at least one terminal vinyl or ethynyl group per oligomer chain.
Analogously, an oligomer [MHP].sub.n formed from a MHP contains from about 2 to about 100 repeating units, each having the formula --MHP-R.sup.s --, where R.sup.s represents the residue of a linking group. A [MHP].sub.n contains at least three phenyl rings, each with 2,6-inert substituents, each ring linked to another through an O atom, and plural pendant groups in each chain.
My invention is particularly directed to (a) polyfunctionalizing an oligomer of at least one mononuclear or polynuclear DH(T)P, formed by a condensation reaction with a reactive linking group resulting in a repeating unit in which two, same or different, DH(T)P moieties are connected with a linking residue R.sup.s ; and, (b) polyfunctionalizing a [MHP].sub.n, specifically PPO. Chloromethylation is a first step when only pendant functional groups are desired. When both terminal and pendant groups are desired in a [DH(T)P].sub.n one preferably commences with the bisphenolate salts which are essentially insoluble at room temperature, or only soluble in aggressive solvents such as dimethyl sulfoxide (DMSO) at elevated temperatures in the range from about 70.degree. C. to about 150.degree. C. The first step is methylarylation, preferably benzylation, of the PAPE's chain ends, followed by halomethylation and subsequent polyfunctionalization. As defined herein, Ph-terminated polyphenylene (PP) is an oligomer of a dihydricphenol (DHP), namely 1,4-dihydroxybenzene or hydroquinone (HQ) which may have inert substituents, and Ph-terminated poly(phenylene oxide), is an oligomer of 2,6-dimethylphenol; or, PPO oligomers which are R.sup.s -linked.
PPO is a particular example of a MHP in which the R.sup.s is the residue of the same MHP, or a similar oligomer in which the residue may be of another mononuclear MHP having some inert ring substituents.
I know of no instance where a PAPE oligomer has been provided with pendant vinyl or ethynyl groups on the electron-rich phenyl group in a repeating unit. Nor do I know of one where a sodium or potassium salt or other bisphenolate of a di-Ph terminated DH(T)P oligomer has been prepared which is substantially insoluble in commonly available organic solvents at room temperature, yet has been used in a modified Williamson etherification which provides the oligomer with benzyl or methylnaphthalene chain ends as a first step, and is subsequently polyfunctionalized in additional steps, so that pendant vinyl groups are provided in the backbone as just stated, and in addition, terminal vinyl groups are provided on electron rich residues of the chain ends. The process of my invention provides for such reactions with a large variety of PAPE oligomers including poly[DH(T)P] linked through a number of different R.sup.s linking groups, particularly those reactions providing pendant vinyl and ethynyl groups, irrespective of the type of the oligomers' chain ends which will affect the yields obtained.
Among these PAPE oligomers are (a) aromatic polyether and polythioether sulfones (all referred to as "APS" for brevity) in which the R.sup.s is a diphenyl sulfone (DPS) residue of a dihalophenyl sulfone (DHPS) linking group; (b) PPO oligomers, optionally linked with a diphenoquinone linking group, as disclosed in "Reactions of Poly(phenylene Oxide)s with Quinones. I. The Quinone-Coupling Reaction Between Low Molecular Weight Poly(2,6-Dimethyl-1,4-phenylene oxide) and 3,3',5,5'-tetramethyl-4,4'-Diphenoquinone", by Dwain M. White, Jour. of Polym. Sci., Polym. Chem. Ed., Vol 19, 1367-1383 (1981); and (c) aromatic polyethers and thioethers in which the R.sup.s is not a sulfone. When the DHP is bisphenol A, and the R.sup.s is DPS, the repeating unit is bisphenol A sulfone ("BPAS"); when the DHTP is bisthiophenol A, the repeating unit is bisthiophenol A sulfone ("BTPAS"), both of which sulfones are together referred to herein as `bis(thio)phenol A sulfones`, and for brevity, "B(T)PAS". To obtain the polyfunctional PAPE oligomers with both terminal and pendant functional groups, salts of a wide spectrum of DH(T)P oligomers with terminals OH or SH groups are etherified to contain terminal methylaryl groups, and more preferably benzyl end groups, which benzyl-terminated oligomers are then polyfunctionalized.
Details of the analysis of the oligomers and a discussion of the results obtained will be found in an article titled "Functional Polymers and Sequential Copolymers by Phase Transfer Catalysis. 3. Synthesis and Characterization of Aromatic Polyether Sulfone and Poly(2,6-dimethyl-1,4-phenylene oxide) Containing Pendant Vinyl Groups" by Virgil Percec and Brian C. Auman, Makromol. Chemie., and in another article titled "Aromatic Polyether Sulfones with Terminal or Pendant Styrene Groups: A New Class of Thermally Reactive Oligomers" by Virgil Percec and Brian C. Auman, Polymer Preprints, 25, No. 1, April 1984, and in references cited therein, relevant portions of which are incorporated thereto as if fully set forth herein.